package com.example.springboot.utils.encrypt;

import lombok.extern.slf4j.Slf4j;

import java.security.MessageDigest;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;

/**
 * @Description: TODO MD5加密
 * @Date: 2018-12-14 14:44:38
 * @author: fengyuan
 */
@Slf4j
public class MD5Util {
    /**
     * 字符编码
     */
    private static String charset = "UTF-8";

    /**
     * 创建md5摘要,规则是:按参数名称a-z排序,遇到空值的参数不参加签名。
     */
    @SuppressWarnings("rawtypes")
    public static String createSign(SortedMap<String, String> packageParams, String elecSign) {
        StringBuffer sb = new StringBuffer();
        Set es = packageParams.entrySet();
        Iterator it = es.iterator();
        while (it.hasNext()) {
            Map.Entry entry = (Map.Entry) it.next();
            String k = (String) entry.getKey();
            String v = (String) entry.getValue();
            if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) {
                sb.append(k + "=" + v + "&");
            }
        }
        sb.append("key=" + elecSign);
        log.warn("md5 sb:" + sb);
        String sign = MD5Util.MD5Encode(sb.toString(), charset).toUpperCase();
        log.warn("签名:" + sign);
        return sign;
    }

    public static String createSignTest(SortedMap<String, String> packageParams, String elecSign) {
        StringBuffer sb = new StringBuffer();
        Set es = packageParams.entrySet();
        Iterator it = es.iterator();
        while (it.hasNext()) {
            Map.Entry entry = (Map.Entry) it.next();
            String k = (String) entry.getKey();
            String v = (String) entry.getValue();
            if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) {
                sb.append(k + "=" + v + "&");
            }
        }
        sb.append("key=" + elecSign);
        log.warn("md5 sb:" + sb);
        String sign = MD5Util.MD5Encode(sb.toString(), charset).toUpperCase();
        log.debug("原串：{} 签名：{}", sb, sign);
        return sign;
    }

    private static String byteArrayToHexString(byte b[]) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));
        }

        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n += 256;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    public static String MD5Encode(String origin, String charsetname) {
        String resultString = null;
        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            if (charsetname == null || "".equals(charsetname)) {
                resultString = byteArrayToHexString(md.digest(resultString.getBytes()));
            } else {
                resultString = byteArrayToHexString(md.digest(resultString.getBytes(charsetname)));
            }
        } catch (Exception exception) {
        }
        return resultString;
    }

    private static final String hexDigits[] = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};

}
